1. Field of the Invention
The invention relates to traffic condition detection by vehicle-to-vehicle communication systems. More particularly, the present invention relates to a method and apparatus for detecting and diffusing traffic condition information by distributed vehicle-to-vehicle communication systems.
2. Description of the Related Art
It is well known in traffic management that unwanted traffic conditions, such as traffic jams may cause road safety problems as well as economic loss. The road safety problems are due to a vehicle approaching an unexpected end of a traffic jam, as the vehicles in front of the vehicle are driving with a lower speed or have came to a complete halt at all. Besides that, traffic jams may also cause an economic loss, as the overall efficiency of traffic is reduced so that goods and services may not arrive in time and such a delay may impose further costs.
In order to overcome the above, two main solutions exist, namely to construct an improved road infrastructure or to enhance the travel efficiency on the existing road infrastructure. Usually, the first solution is avoided, as it imposes very high costs and has a large impact on the environment, which effects and costs in the future can not be estimated by now. Accordingly, the second solution attracts nowadays more and more attention.
As traffic management is one of the main methods for this solution, traffic condition information is becoming more and more important for an efficient traffic management. With the knowledge about the traffic condition, travelers in their vehicles can adapt their route to avoid any unwanted traffic condition, such as a jam or stop-and-go traffic. Additionally, traffic management operators can take countermeasures so that any unwanted traffic condition can be resolved (e.g. controlling of traffic lights, imposing speed limits, detours, etc.) and inform the travelers accordingly.
At present, traffic conditions are detected and diffused by centralized traffic management control centers using traffic message channel (TMC). Accordingly, sensors have to be equipped at the road infrastructure and/or on the vehicles that collect data about traffic flow and transmitters send such data to the travel management centre via a pre-installed communication infrastructure. In the traffic management centre the data is analyzed using special algorithms to attain the traffic condition information. This information is then sent to the travelers en route and the traffic management operators again via a pre-installed infrastructure. As this method requires a dedicated road side infrastructure, due to costs it is only available on highways but not on urban or rural roads. Accordingly, traffic condition information is not available to travelers once they left the highway. Even on the highway, it can happen that drivers of a vehicle approaching a traffic condition do not know about said condition as said traffic condition has occurred recently, and not been processed yet at the travel management centre (cf. safety problem).
In WO 2005/5004080 a system for automatic detection and report of a sudden traffic jam is described, wherein roadside communication units are used that are installed along the highway to collect the probe data of the passing vehicles. Each vehicle is equipped with a communication device that has been pre-registered by a travel management operator. The collected information will be then sent to the travel management control centre for data analysis and traffic jam detection. The described system uses a road side unit every two kilometers and a travel management control centre that collects and analyses the data of vehicles. Accordingly, the costs of such an implementation are very high.
WO 2004/027729 relates to a method and system for detecting and estimating road traffic from location data of mobile terminals in a radio communication system. Such a method and system imposes said deficiencies that also a travel management control centre is needed and that the position of the mobile terminals has to be matched with a digital map, imposing additional costs. Further, only the movement of the mobile terminal itself is detected but no information about the surrounding terminals is exchanged.
JP 2002/090165 describes a traffic jam detection device using an onboard sensor in a vehicle to detect the present location at an instant and calculate two different average speeds from the present location based on two different time intervals. According to the two different average speeds, the device determines if the vehicle is in traffic jam or not. However, as the device only takes in consideration the behavior of the vehicle it is mounted on, the overall traffic condition can not be determined.